Heating cartridge



Oct. 11,- 1932. 5.1.." LUBELSKY HEATING CARTRIDGE Filed May- 16, 1929Ben LLUbeISkg u r/I 'l ?atented BEN L. LUBEL, 0F PITTSBURGH,PENNSYLVANIA, ASSIGNOB TO SAFETY MTNTNG COANY, 01E CHICAGO, ILLINOIS, AOOBL'OBATION TING *GARTBIDGE Application filed Hay 1a, 1929. Serial no.868,545.

The present invention is concerned with the production of heat inpredetermined quantities and within relatively short predetermined timeintervals and the same is applicable to any use involving theseconditions.

One very advantageous use of the heating means of the present inventionis in connecshown in the copending application of Dent Ferrell andArthur W. Helmholtz, Serial No. 169,441, filed February 19, 1927 and forpurposes of illustration the present invention is herein shown asapplied to a cartridge of this general type.

In blasting cartrid es of the type referred to the blasting me ium is aliquefied as such, for example, as carbon dioxide an it is essentialthat this medium be raised to its critical temperature racticallyinstantaneously in order to pro uce a substantially in-- stantaneouspressure "increase such as will operate the venting means of thecartridge and suddenl liberate the entire gaseous char e. A s owincrease of pressure due to the s ow development of heat within thecartlldie will result in an incomplete operation 0 t tive discharge ofthe cartridge.

Accordingly it is an object of this invention to provide a. means whichis capable of producing a substantially predetermined amount of heat ina practically instantaneous manner.

It is also an object of the present invention .to provide a heatproducing compound which is not sufiici'ently sensitive to friction andshocks to render the manufacture or handling of the same unsafe.

A further object of the invention is to provide a com ound of thecharacter described which is re atively stable, that is, one whichtridge containing a charge of liquefied gas under pressure and operativeto efiect a substantially instantaneous vaporization of the charge.

e venting means and hence an inefiec-- Other more specific objects willap ear in connection with the following detai ed description.

In the drawing,

Figure 1 is a view in longitudinal section of a blasting cartridge ofthe type hereinabove referred to and showing the improved tion appliedthereto.

Figure 2 is an enlarged detailed view of the heat producing unit.

Referring to the drawing, it will be noted that the present invention isdisclosed as embodied in a cartridge comprisin a casing having arupturable disc 11 and a directing cap 12 at the discharge end and means13 for establishing an electrical connection for the heating element andfor introducin the blasting medium into the interior 14 o the cartridge.The cartridge construction will not herein be described in detailinasmuch as it is substantially the same as that shown in the copendinga plication above referred to.

The heat pro ucing unit 15 is ada ted to be inserted in the positionshown in igure 1 with its electrical connection 16 at one end thereof incontact with the rupturable disc 11 and the electrical connection 17 atthe opposite end thereof in contact with the plate 18 constituting theother terminal for the electrical circuit.

Referring particularly to Figure 2, it will bc'observed that the heatproducing unit structurally consists of a substantiall tubular container19 within which the heating compound or mixture 20 isplaced. The opositeends of this tube are referably closed y means of lugs 20' which. may beformed of wood, cor or any other suitable material. The container 19 ispreferably formed of waxed paper or some other combustible material. Thecontacts 16 and 17 are formed on the respective ends of an electricalconductor 21 which passes entirely through the heating device from endto end. Any suitable arrangement may be made for accommodating theconductor at the opposite ends of the heating unit and as herein shown,the conducting wire simply passes between the casing 19 and the closingplugs 20'. The

- heat producing device of the present invention with blastingcartridges of the type and especially for use in connection with,

of the chlorate, perchlorate or nitrate groups, I

while the latter may be any suitable metal such, for example, asaluminum, carbon, magnesium or manganese or any suitable combination ofthese.

It has been found from extensive experiments that the perchlorates arefar more suitable for the production of heat in general blastingcartridges of the type referred to. The reason for this is that theperchlorates have a greater oxygen content than do either I thechlorates or nitrates, thus making it possible to secure a given amountof heat with a less amount of the mixture. It has also been found thatperchlorates are substantially more stable than the chlorates and forthis reason their use under a variety of weather conditions is ofconsiderable advantage. From the safety standpoint rchlorates offeradvanta es over either t e chlorates or the nitrates us to the fact thatthe erchlorates are much less sensitive to ignition by friction orshock.

As hereinabove pointed out, there are quite a number of metals suitablefor use as reducing agents. However, it has been found that aluminum isthe most satisfactory for use in this combination. The only diflicultyinthe use of aluminum is due to the fact that its temperature ofignition isrelatively high, thus requiring a considerable amount of heatto energize the mixture. This difli- ,c'ulty is overcome according tothe present invention by addingto the mixture a relatively smallquantity of a different reducing agent which has a relatively lowignition temperature. The most suitable secondary reducing agent thusfar discovered is carbon, although it should be appreciatedthat anyother reducing agent having a low temperature of ignition as comparedwith that of aluminum may be used to serve the same purpose. 18ycombininfigtwo different agents of the character speci d it is necessarto use only suflicient heat to raise the secon ary reducing agent to theoint of i nitionand this a ent then 'ves o the ad itional amount 0 heatrequired to raise the primary reducing agent to its point of ignition.

The mixture which is generally described above may consist either ofsodium perchlorate or potassium perchlorate together with aluminum andcarbon or their equivalents.

It will be appreciated that the proportions in which these ingredientsare used may-be varied in accordance with the work to be done. Thefollowing are examples of mixtures which have been found to beparticularly suitable for use in connection with charged blastingcartridges. It will be n that one of these mixtures embodies sodiumperchlorate whereas the other is based upon potassium perchlorate.

79.8% sodium perchlorate 14.65% aluminum 5.7% carbon It should beappreciatedthat the heat producing compound of the present invention maybe put up in any desired form according to the requirements of differentkinds 0 work. For use in connection with blasting cartridges it has beenfound desirable to enclose the heat producing mixture in acartridgc-like tube as shown in the drawing The tube ma either be filledcompletely wi the heat pr ucing mixture orit may be filled in part bysome inert substance such as fullers earth in case a less amount of heatis re.-

quired. In the present instance, where the compound is encased in apaper cartridge, it is desirable to re ard the paper or other materialof which t e casing is made as a part of the reducing agent of thecompound and to calculate the proportions of oxygen carrier and reducingagent so as to provide for the complete combustion of the container. Theaction of the improved heat roducing device should be apparent from t eforegoing description but may be briefly characterized as follows:

When it is desired to energize the heating device it is merel source ofcurrent t ereto so that the squib or matchhead 22 will be ignited. Theheat produced by the squib or matchhead serves to raise the temperatureof the reducing agents to the point of ignition and at the same timecauses the oxygen carrier to give ofi free oxygen which then combineswith the reducnecessary to connect a Ill ing agents to producecombustion. Once this combustion has been started it continues until theentire heating unit is consumed and in this way the amount of heat forwhich the particular heater has been designed is generated in apractically instantaneous manner.

By varying the amount of mixture used, the" amount of heat roduced eanbe controlled within very fine imits.

It will be obvious to those skilled in the art that modifications can bemade in the do tails and in the use of chemical equivalents, as well asin the matter of the structural form of the invention. Therefore, theinvention is aaaaaas not to be regarded as limited in any way other thanby the state of the prior art andas the appended claims may require.

I claim:

1. A heater for carbon dioxide blasting cartridges comprising a tubularaper container, closures for the ends of sai container, an electricigniting device within said container and having leads extending to theexterior thereof, and a chemical mixture within said container to beignited by said i niting device and rapidly produce high eat, saidmixture comprising potassium perchlorate, aproximately aluminumapproximatel 14% and carbon approximately 6%.

2. X heater substantially as set forth in claim 1, characterized in thatthe quantity of potassium perchlorate is calculated to provide an excessof oxygen.

Signed at Chicago, this 14th day of May,

BEN L. LUBELSKY.

